dts: cpu: add device tree bindings for Synopsys ARC-V RISC-V CPUs

Add device tree binding files for the Synopsys ARC-V RHX and RMX RISC-V
CPU cores. These bindings enable proper device tree property parsing by
the Enhanced Device Tree (EDT) system, allowing Kconfig device tree
macros to access CPU properties like clock-frequency.

The bindings include the standard RISC-V CPU properties by extending
riscv,cpus.yaml, which provides access to properties defined in cpu.yaml
such as clock-frequency.

Signed-off-by: Afonso Oliveira <afonsoo@synopsys.com>

Author: AFOliveira

boards/snps/nsim/arc_v/Kconfig.defconfig

@@ -6,9 +6,6 @@ if BOARD_NSIM_ARC_V_RMX100
 config SYS_CLOCK_TICKS_PER_SEC
 	default 1000
 
-config SYS_CLOCK_HW_CYCLES_PER_SEC
-	default 5000000
-
 endif # BOARD_NSIM_ARC_V_RMX100
 
 if BOARD_NSIM_ARC_V_RHX100

dts/bindings/cpu/snps,av5rhx.yaml

@@ -0,0 +1,8 @@
+# Copyright (c) 2024 Synopsys, Inc.
+# SPDX-License-Identifier: Apache-2.0
+
+description: Synopsys ARC-V RHX RISC-V CPU
+
+compatible: "snps,av5rhx"
+
+include: riscv,cpus.yaml

dts/bindings/cpu/snps,av5rmx.yaml

@@ -0,0 +1,8 @@
+# Copyright (c) 2024 Synopsys, Inc.
+# SPDX-License-Identifier: Apache-2.0
+
+description: Synopsys ARC-V RMX RISC-V CPU
+
+compatible: "snps,av5rmx"
+
+include: riscv,cpus.yaml

soc/snps/nsim/arc_v/rmx/Kconfig.defconfig

@@ -3,6 +3,9 @@
 
 if SOC_SERIES_NSIM_ARC_V_RMX
 
+config SYS_CLOCK_HW_CYCLES_PER_SEC
+	default $(dt_node_int_prop_int,/cpus/cpu@0,clock-frequency)
+
 config RISCV_SOC_INTERRUPT_INIT
 	default y